What is the role of antimicrobial peptides (AMPs) in the pathophysiology of rosacea?

AMPs are small molecular weight proteins that are a part of the innate immune response and have demonstrated broad-spectrum antimicrobial activity against bacteria, viruses, and fungi. They are rapidly released upon injury and/or infection of the skin, and they have been implicated in the pathogenesis of many inflammatory skin diseases. Cathelicidins and β-defensins are 2 well-known types of AMPs, of which the former has been shown to be expressed in abnormally high levels in patients with rosacea.

Specifically, the LL-37 peptide form of cathelicidin, in addition to proteolytically processed forms of LL-37, have been found in significantly different amounts in rosacea patients compared with healthy individuals. LL-37 is expressed by polymorphonuclear leukocytes and lymphocytes. LL-37 interacts with endothelial cells and stimulates angiogenesis both in vitro and in vivo. It also modulates the expression of VEGF.
[10] Injection of LL-37 and these novel peptides derived from LL-37 into mice induced inflammation, erythema, and telangiectasia; therefore, researchers hypothesized that an excess of cathelicidins coupled with abnormal processing caused disease.
[15]

Galderma. Efficacy and safety of CD5024 1% cream versus metronidazole 0.75% cream in subjects with papulopustular rosacea over 16 weeks treatment, followed by a 36-week extension period (ATTRACT). ClinicalTrials.gov. Available at http://clinicaltrials.gov/ct2/show/NCT01493947. Accessed: August 21, 2014.

Disclosure: Received consulting fee from Galderma for consulting; Received consulting fee from Valeant for consulting; Received consulting fee from Promius for consulting; Received consulting fee from Anacor for consulting; Received grant/research funds from Stiefel for investigator; Received grant/research funds from Astellas for investigator; Received grant/research funds from Ranbaxy for other; Received consulting fee from Ranbaxy for consulting.

Acknowledgements

The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous authors, Ravi Ratnavel, MD, Mana Ogholikhan, MD, and Saurabh Singh, MD, to the development and writing of this article.